Update docker-compose.yaml

change repository from `vineeth` to `timescale`

Author: VineethReddy02

docker-compose/promscale-demo/docker-compose.yaml

@@ -75,7 +75,7 @@ services:
       - "16686:16686"
 
   grafana:
-    image: vineeth97/promscale-demo-grafana
+    image: timescale/promscale-demo-grafana
     restart: on-failure
     volumes:
       - grafana-data:/var/lib/grafana
@@ -152,4 +152,4 @@ services:
 
 volumes:
   timescaledb-data:
-  grafana-data:
+  grafana-data: